The invention relates to a feed device for granulated and powdery welding powders and additives on a welding tractor for arc welding on vertical to horizontal, curved surfaces using at least one welding powder vessel, as well as supply lines for powder application upon the weld zone and for covering the arc.
In a known use of endless base electrodes for arc welding under a powder seal endless bare electrodes which by means of a feed, are continuously advanced into the weld zone from a wire drum. The entire weld zone and the tips of the electrodes have to be covered with granulated or powdery weld powder and hidden from the surrounding atmosphere.
Obtaining the powder seal of the entire weld zone in arc welding on vertical and curved surfaces may be regarded as solved by the use of prior art devices disclosed, for example, by West German Pat. No. 930,939. To some degree, these known devices are suitable for the production of spherical large size vessels.
Despite the known state of the art, electrogas and electroslag welding useable, for example for manufacturing spherical pressure vessels is still not feasible, as the safe feeding of welding powder and metal powder is not assured. Difficulties in the automatic welding of the vessel jacket sections arise because the required uniform continuous powder supply cannot be effected with known welding machines due to the constant variation of the angle of inclination of the welding tractor in the production of vertical curved seams, from the vertical to the horizontal plane.
It is further known, for example, through West German Pat. No. 10 14 248, how to discharge welding powder by means of a partly evacuated vessel producing a suction effect. These known devices, however, are unsuitable for electrogas and electroslag welding for the reasons that, in the region of powder application in the weld zone, air from the atmopshere flows into the powder cover due to the existing pressure difference. Thereby, the powder cover is loosened up and the required tight powder scaling against the atmosphere is no longer ensured, owing to which considerable deficiencies in the weld seam quality are known to result.